Isovector axial and pseudoscalar form factors from twisted mass lattice QCD at the physical point

We present the isovector axial, induced pseudoscalar, and pseudoscalar form factors of the nucleon using three twisted-mass fermion ensembles with degenerate up- and down-, strange-, and charm-quarks with masses tuned to their physical values (physical point). The three ensembles have lattice spacing $a$=0.08, 0.068, and 0.057 fm and approximately equal physical volume allowing for the continuum limit to be taken at the physical point. Excited-state contributions to the matrix elements are evaluated using several sink-source separations from 0.5 fm to 1.5 fm and multistate fits. We check the partially conserved axial-vector current (PCAC) hypothesis and the pion pole dominance (PPD) and show that in the continuum limit both relations are satisfied. We provide results at the continuum limit for the isovector nucleon axial charge, axial radius, pion-nucleon coupling constant, and for the induced pseudoscalar form factor at the muon capture point.

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Publication Details

Published
2025-02-10
DOI
https://doi.org/10.22323/1.466.0330
Primary Topic
Quantum Chromodynamics and Particle Interactions
Type
article
Field-Weighted Citation Impact
0.00

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article

Isovector axial and pseudoscalar form factors from twisted mass lattice QCD at the physical point

Carsten Urbach, Bartosz Kostrzewa, Jacob Finkenrath, Gregoris Spanoudes et al.
Quantum Chromodynamics and Particle Interactions
article

Isovector axial and pseudoscalar form factors from twisted mass lattice QCD at the physical point

Carsten Urbach, Bartosz Kostrzewa, Jacob Finkenrath, Gregoris Spanoudes, Giannis Koutsou, Simone Bacchio, Martha Constantinou, Constantia Alexandrou, R. Frezzotti
article en

Abstract

We present the isovector axial, induced pseudoscalar, and pseudoscalar form factors of the nucleon using three twisted-mass fermion ensembles with degenerate up- and down-, strange-, and charm-quarks with masses tuned to their physical values (physical point). The three ensembles have lattice spacing $a$=0.08, 0.068, and 0.057 fm and approximately equal physical volume allowing for the continuum limit to be taken at the physical point. Excited-state contributions to the matrix elements are evaluated using several sink-source separations from 0.5 fm to 1.5 fm and multistate fits. We check the partially conserved axial-vector current (PCAC) hypothesis and the pion pole dominance (PPD) and show that in the continuum limit both relations are satisfied. We provide results at the continuum limit for the isovector nucleon axial charge, axial radius, pion-nucleon coupling constant, and for the induced pseudoscalar form factor at the muon capture point.

U.S. Department of Energy, University of Texas at Austin, University of Cyprus, European Commission, Deutsche Forschungsgemeinschaft, Research and Innovation Foundation, Centro Svizzero di Calcolo Scientifico, National Supercomputing Centre Singapore, Gauss Centre for Supercomputing, European Regional Development Fund, Nuclear Physics
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Quantum Chromodynamics and Particle Interactions
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